Lots of useful information about the system is held in pseudo filesystems and presented using the seq_file mechanism. Unfortunately during both boot up and kernel panic (both good times to break out kdb) it is difficult to examine these files. This patch introduces a means to display sequence files via kdb.
Signed-off-by: Daniel Thompson daniel.thompson@linaro.org --- include/linux/kdb.h | 5 +++++ kernel/debug/kdb/kdb_io.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 56 insertions(+)
diff --git a/include/linux/kdb.h b/include/linux/kdb.h index 290db12..fb46dd4 100644 --- a/include/linux/kdb.h +++ b/include/linux/kdb.h @@ -25,6 +25,7 @@ typedef int (*kdb_func_t)(int, const char **); #include <linux/init.h> #include <linux/sched.h> #include <linux/atomic.h> +#include <linux/seq_file.h>
#define KDB_POLL_FUNC_MAX 5 extern int kdb_poll_idx; @@ -117,6 +118,8 @@ extern __printf(1, 0) int vkdb_printf(const char *fmt, va_list args); extern __printf(1, 2) int kdb_printf(const char *, ...); typedef __printf(1, 2) int (*kdb_printf_t)(const char *, ...);
+extern int kdb_print_seq_file(const struct seq_operations *ops); + extern void kdb_init(int level);
/* Access to kdb specific polling devices */ @@ -151,6 +154,8 @@ extern int kdb_register_repeat(char *, kdb_func_t, char *, char *, extern int kdb_unregister(char *); #else /* ! CONFIG_KGDB_KDB */ static inline __printf(1, 2) int kdb_printf(const char *fmt, ...) { return 0; } +static inline int +kdb_print_seq_file(const struct seq_operations *ops) { return 0; } static inline void kdb_init(int level) {} static inline int kdb_register(char *cmd, kdb_func_t func, char *usage, char *help, short minlen) { return 0; } diff --git a/kernel/debug/kdb/kdb_io.c b/kernel/debug/kdb/kdb_io.c index 14ff484..c68c223 100644 --- a/kernel/debug/kdb/kdb_io.c +++ b/kernel/debug/kdb/kdb_io.c @@ -850,3 +850,54 @@ int kdb_printf(const char *fmt, ...) return r; } EXPORT_SYMBOL_GPL(kdb_printf); + +/* + * Display a seq_file on the kdb console. + */ + +static int __kdb_print_seq_file(struct seq_file *m, void *v) +{ + int i, res; + + res = m->op->show(m, v); + if (0 != res) + return KDB_BADLENGTH; + + for (i = 0; i < m->count && !KDB_FLAG(CMD_INTERRUPT); i++) + kdb_printf("%c", m->buf[i]); + m->count = 0; + + return 0; +} + +int kdb_print_seq_file(const struct seq_operations *ops) +{ + static char seq_buf[4096]; + static DEFINE_SPINLOCK(seq_buf_lock); + unsigned long flags; + struct seq_file m = { + .buf = seq_buf, + .size = sizeof(seq_buf), + /* .lock is deliberately uninitialized to help reveal + * unsupportable show methods + */ + .op = ops, + }; + loff_t pos = 0; + void *v; + int res = 0; + + v = ops->start(&m, &pos); + while (v) { + spin_lock_irqsave(&seq_buf_lock, flags); + res = __kdb_print_seq_file(&m, v); + spin_unlock_irqrestore(&seq_buf_lock, flags); + if (res != 0 || KDB_FLAG(CMD_INTERRUPT)) + break; + + v = ops->next(&m, v, &pos); + } + ops->stop(&m, v); + + return res; +}